Need guidance guidance...

[BLCMulcher]

I've got to clear three dead straight 20' by 2300' roadways through the woods and will utilize my Fecon 148. I know my starting and ending point for each row and I wanted to solicit some opinions regarding how to get from point a to b efficiently. Surveyor flagging is not in my budget nor is it feasable because the vegetation is extremely thick.

I assume some sort of gps is my only option. I've tried basic hand help gps systems and they are not nearly accurate enough from the cab and under the tree canopy.

If gps is your anser what are this type of gps called and where can you purchase them?

-Thanks

 

[CurlyDave]

What is the tolerance on "dead straight"? And what is the tolerance on where the end of the road is if you start at a known beginning?

I am not convinced that a hand held anything is going to be good enough, but it really depends on tolerances.

For instance, if you can be off by 20' at 2300 feet, that is 0.50 degrees.

A high-quality compass might be able to accomplish this, but you are not going to be able to mount it on a machine -- too much iron and steel too close to the compass.

If you are only allowed an error of 1' the problem becomes much harder.

Anyway, the GPS equipment you might be interested in is called High Precision GPS. If you find a good surveyor supply house they will be able to help.

There is a learning curve in figuring out how to use the high precision stuff, which you should consider.

 

[WestshoreConstruction]

The only way to not be liable is to hire a survey crew , it always has to be part of your budget or make the customer mark it out. There's no cheap way to do it after the fact. Unfortunately this
Might be a steep learning curve for ya. We use Garmin 276 handhelds with a external antenna and with some practice you can be almost dead on. By dead on I mean in 1 mile within +- 20'.

 

[fishfactor]

We use a simlilar setup as Westshore. Garmin 62S handheld with a antena that mounts on the roof of the cab. You can get close on the first pass, just be sure to back up a lot to give the GPS a view of the sky in the path that you have already cleared. When you get close to the end, have a spotter stand at the end point and guide you by radio. Your first path may not be perfectly straight. When you go back to widen, you can fix the bends by taking off more from one side than the other. We can typically get good results using this method.

But... if it is imperative, hire a survey crew. That takes the liability off of you. The high precision GPS mentioned will cost way more that hiring a surveyor. A setup for one of our machines to achieve pinpoint accuracy was going to be in the $10,000 range.

 

[JamesHW]

I guess my approach would depend on what my liability was. If these almost 4 1/2 mile roads were being laid out on my own land and I wanted to do the survey myself, I might try a combination of GPS, a good compass and perhaps a laser transit. I'd use the combination of the GPS and measuring tape to traverse the center line of the road from point a to be, placing a stake periodically to mark the path. Then I would follow up to get the line as precise as possible. Of course thise approach would need a second person to assist and would be time consuming. If the path is heavily wooded with a lot of brush, it would become even harder and more time consuming. Any hills or ravines in the path would add more difficulty, but I assume since the plan is for straight roads, the land is relatively flat. You might want to read the basic Army manual on surveying to get an idea of what's involved. Also getting copies of any existing USGS maps of the land to assist in plotting out your roads. I've always been interested in surveying (the ancestor I was named after was the Surveyor General of Vermont in the 1700's) and practice rediscovering the borders of my property, primarily in order to properly post the property.

If a professional surveyor is engaged to mark out the path I can assume the cost would be high. Laying out what amounts to over 26 & 1/2 miles aint going to be cheap. I was quoted 7 grand to survey the border of my 78 acres, which I would estimate as running less than 2 miles in length, although that include a 50 foot deep ravin to raverse at one corner and five lots totlaing about 7 acres cut out of the original platt that were sold by my Mom over the years. We have waited until we go forward getting permits to build our new house on the property since I suspect the town will want a new survey then.

 

[grsthegreat]

Sorry, but if you want dead straight....its probably going to be transit.

It sucks, and is alot of work, but nothing is straighter or truer. I did this for all my fencelines. After going 1280' thru my sloping forested property, i came out within 4" of the survey stake on the other side....cant ask for more than than in 1/4 mile.

 

[tonyoz]

I think Trimble make a handheld GPS that is more accurate than the Garman but costs a fare bit more, have a client hire one from them and worked OK under trees.

 

[Ken45101]

I don't think you can do anything this precise with a standard GPS. I forget the term, but I believe surveyors utilize another box which gives a more precise local signal.

Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations.

DGPS uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. These stations broadcast the difference between the measured satellite pseudoranges and actual (internally computed) pseudoranges, and receiver stations may correct their pseudoranges by the same amount. The digital correction signal is typically broadcast locally over ground-based transmitters of shorter range.

I think hacking your way through the woods with a transist is your best case, or can you clear an initial path using a compass so that you can then see well enough to use a transit?

 

[TroySD]

I sell the precision guidance equipment for a living. What you are looking for is a Light bar. Trimble Navigation or Ag Leader is what we sell. Depending on the accuracy level you are looking for you could find a used unit for couple hundred bucks up to the $25,000 systems I install on the Ag tractors.

Hand held gps units are only +- 3m accurate at absolute best.

The lightbars have 3 basic accuracy levels:
(All have differential corrections which is what you need for your project. DGPS)

WAAS - Wide Area Augmentation System - +- 6-8" accuracy
Omnistar or SF2(Deere) - +-2-5" accuracy
RTK - <1" accurate (requires base station, also used in GPS Surveying)


If 6-8" accuracy is all you need go for a used EZ Guide Plus, they are old but reliable and real cheap to pick up.

If you have questions holler at me.

 

[lj04]

I sell the precision guidance equipment for a living. What you are looking for is a Light bar. Trimble Navigation or Ag Leader is what we sell. Depending on the accuracy level you are looking for you could find a used unit for couple hundred bucks up to the $25,000 systems I install on the Ag tractors.

Hand held gps units are only +- 3m accurate at absolute best.

The lightbars have 3 basic accuracy levels:
(All have differential corrections which is what you need for your project. DGPS)

WAAS - Wide Area Augmentation System - +- 6-8" accuracy
Omnistar or SF2(Deere) - +-2-5" accuracy
RTK - <1" accurate (requires base station, also used in GPS Surveying)


If 6-8" accuracy is all you need go for a used EZ Guide Plus, they are old but reliable and real cheap to pick up.

If you have questions holler at me.

Over what distance are those accuracies given for?

 

[TroySD]

Those are pass to pass accuracy, The point A to point B line is theoretically infinite. We use them for high accuracy farming applications such as applying fertilizer in a band in the fall and then planting directly on that spot in the spring 6 months later.

I have customers that will travel 1-3 miles and retain that accuracy with the Omnistar or RTK levels.

WAAS can be a tricky beast as its accuracy is easily manipulated by environmental conditions, ie sun spots, gps constellations and many many more.

It would easily build your road in my opinion.

 

[BLCMulcher]

Thanks to all for the info, ideas and suggestions.

To clarify things a little my client wants the 20' rows straight so he can see down them. I want dead straight to avoid clearing land unnecessarily.

My experience with a common hand held in these conditions is one second you are sitting on line and the next you are off 30'

It sounds like a middle end gps is the most practical solution. I seem to be getting more of this type of work so maybe I should get a unit with a cab mounted display and external antenna for accuracy. Also common for me is to cut a property line from one boundary point to another and because of thick foliage I don't have access to either point prior to clearing - but I do have lat/long points. So any sytem I buy will have to accept lat/long as waypoints which I can normally get my hands on.

If I required a surveyor to flag the cut for me 4 out of 5 jobs would never happen or I would lose the work to a competitor. And I am speaking of jobs here where neither the client nor the friendly neighbor minds if I clear more land than I am getting paid to clear - not the construction/developer client that normally has my work flagged off for me.

Looks like the EZ Guide 250 would do the trick if it will accepts lat/long input. Anyone need to sell one?

-Thanks Again...

 

[AGGIE00]

We use a topcon legacy in the cab with pga1 antenna mounted on top. With that we use a carlson data collector which is what gives the map for guidance. This is RTK and requires a base station which for us is a trimble unit or we will use a data modem to tie into the network. The cost of all this equipment is quite high and we only justify it because we are surveyors too. For what you are doing I would use a lesser handheld to make the first pass and get line of sight so you can get it straightened out.

 

[GordonW]

We use an Outback lightbar and I wouldnt trade it for the world. We have made 4 to 5 mile passes that had to line up with other ROWs and can stay dead on. The only thing is the cost.

 

[TroySD]

Andy,

How's it working for you? Hadn't heard from you in a while, thought I'd check in.

Troy